j_s_poirier

I currently have an OS 55AX. Originally I mounted it in a Nitroplanes Edge 540T. The engine would stall after a minute or two of flying. I was using 10% CoolPower and a 12x6 Evo Prop. I disassembled the the whole fuel system, replaced the glowplug, etc. The engine continued to stall after a couple of minutes of flying. The fuel tank was padded and assembled properly each time. I used a tachometer to find the peak RPM and then richen the mixture until the RPM's dropped about 500-700 for prop-unloading. After being fed up with fixing that plane, I purchased a new one of the same model. Prior to flight I found peak RPM at 22,200and richened the mix down to 21,420. I flew 2 racetracks, performed 2barrel rolls in each direction, and one inside loop. On the last fly by(2min 25sec in) the engine stalled and this plane also crashed. What isgoing on??? Your help is greatly appreciated.

freakingfast

My Feedback: (3)

Your tach numbers are wrong, so look into to that. You may be over heating. How big is the cowl outlet? It should have3 times larger area than the inlet. Also, block off the inlet opposite the cylinder. Loose that big lumber, the engine is not in its power band, it's lugging. Try a Master Airscrew 11X7 S-2 type, second choice 11X6 APC. I stay away from Coolpower like the flu. I run almost anything but that.

Good luck

captinjohn

I agree..Tack numbers are wrong...too high. Get somebody to check the RPM with a different tack! Capt,n

freakingfast

My Feedback: (3)

Maybe he had it set for 4 blade.

DarZeelon

JS,


I second (and third...) what was already written by John and FF...

1. 'CruelPower' is NOT the right fuel for your engine! Period!
Trade it, or give it away to someone that has a YS four-stroke, NOW!
Don't keep using it as it is, even if there is no other fuel available.
Get some Omega, Sig Champion, PowerMaster GMA, or any other fuels that contains enough castor oil (not just a decorative amount...)!

2. Throw your tachometer to the trash-bin... Spinning a 12x6 prop at 22,200 RPM requires that your engine produce 8.66 HP. IT IS NOT!
People here would be very thankful, if their OS.55AX spun a prop 100 RPM faster than its siblings...
Reporting 10,000 RPM faster, would just have you labeled as a reputable liar...[:'(] You are new here and you don't want that...

A 12x6 APC @ 12,200 RPM is a very respectable and quite believable 1.44 HP.


FF,


If you set the tachometer on 4-blades, it would read a 2-blade prop at HALF of the real RPM; not double it...[&:]

j_s_poirier

I appreciate all of the input, but the issue isn't my numbers....it's the fact that the engine keeps stalling no matter what plane I put it in. I've flown it with no cowl at all because I thought it was overheating at first. That wasn't the issue. It is just really frustrating. I've got an Evo .46 in a GP Super Sportster MkII that I've had for 2.5 yrs, no issues, and that turns an 11x7 no prob. Here are some pix to show how it is installed right now:

jimmyjames213

My Feedback: (2)

heres a list of maybe's
bad glow plug
hole in fuel lines
clunk line fall off
tank to low
old fuel
open the head, see if its damaged( post a pic)
junk in carb, need a cleaning?
some engines hate those exhaust extentions, take if off
maybe that prop gets really really flat when spun, thats the only reason i could think of it jumping to that high if a rpm (if the tach is right), try a new prop?

WMB

My Feedback: (1)

I had a few issues with my 55. Head bolts came loose at about 1 1/2 gallons. Easy fix.
This idles so well within a wide range of low end needle settings, mine was too rich and causing a rich midrange. I leaned out the bottom end a bit at a time and the rich midrange went away. It now has about 2 gallons through it. Lots of full throttle to idle and back in flight without a problem. Running great. Hope that helps you a bit.

rainedave

My Feedback: (1)

I had one on my .55 for a few flights and it ran terrible, so off it came. I think this engine is finicky about muffler pressure. If the muffler pressure line comes off or has a leak it will die when you move the throttle.

David

DarZeelon

Mr. Poirier,


Do ALL of the following:

1. Stop using CP and get some fuel with a good deal of castor oil.

2. Throw the tach you have to the trash (I don't care if it is not the issue - it is misinforming you).

3. Throw that Dubro exhaust extension to the trash (I have seen it cost over 1,000 RPM and cause many other problems). You will need to wipe the oil off your plane anyway...

4. Plug the left-hand hole in the cowl (the one not facing the cylinder) and install baffles on the inside (you can use pieces of balsa and 30 minute epoxy), so that air flowing in through the intake, goes down toward the cylinder and the head.

5. Install baffles within the engine compartment (you can use pieces of balsa again), so that the cooling air flows closely and smoothly around the contour of the cylinder and the head; and continues down.

6. Open up the exit hole, to the rear-right hand side, so that the hot air from (5) will have a direct path to a real low-pressure area (the current "exit hole" around the muffler, cannot even be considered a sorry excuse for a bad design).


Air is NOT your subordinate! Having an entry hole and an exit hole in the cowl, does not necessarily mean the cooling-air will 'see' them as such...
Air will flow from a high-pressure volume, to a low-pressure volume.

Even if the cowl holes do apply to the above rule, there is no guarantee that the airflow from the high-pressure intake, to the low-pressure exhaust, will actually flow around the hot parts that need to be cooled...

You need to force that air to take the right route and it is done by using baffles... Look into the cowl of any light piston-engine plane at your local airport, to see the elaborate baffling around the engine.
Without this, it will never fly. It applies to every air-cooled engine you can think of.

Stagnant, hot air in the cowl, will only allow insufficient cooling through convection... Overheating is the only possible result.

Read all about it [link=http://www.supercoolprops.com/articles/cooling_largemodelengines.php]right here[/link].

Trisquire

My favorite Dub Jett quote.

BlackB12

My Feedback: (9)

You checked to see that you didn't switch your fuel and vent lines right?

Mike

j_s_poirier

The lines aren't crossed. I'll just have to bench test it. I flew this engine with no cowl on the first plane when I thought it was overheating.

rcdude7

My Feedback: (264)

Check for air leaks in the NV assy., check the backplate and head screws to ensure they are tight. What plug are you running?

j_s_poirier

A3 Dude

rcdude7

My Feedback: (264)

The A3 is a hot plug, try a #8 instead.

The #8 is what OS supplied with this engine when it was new.

j_s_poirier

that's what is in there then. this thing only has about 7 flight attempts on it

freakingfast

My Feedback: (3)

All good points mentioned above. Loose head screws, loose screws or blown seal at back plate. Bad or wrong glow plug. Just because it starts and runs does not mean the plug is good.

I have an engine that just loves K&B HP or Enya # 5 glow plugs. I knew the plug had time on it and I pulled it to have a look at it. It was a bit mangled and frosted so I elected to change it than, but at that moment I only had a OS R5 so that's what I used. I got it to the field a few days later and it started fine but quit suddenly 2 minutes in to the flight on two flights. I change back to a Enya #5 that I now had and the problem was solved.

Yours should run with a OS # 8, K&B 1-L or Enya #4.

freakingfast

My Feedback: (3)

Change it anyway, one less variable. Some chemicals can contaminate the platinum. Did you use anything(oil) that had silicone or Teflon in the engine?

SeamusG

I had a similar problem with my OS 46 AX installed on my SIG SSE. It ran fine on the bench but during flight it would frequently fail resulting in yet another dead stick. I use a Hobbico panel on my field box and it has a glow plug meter. The installed plug (#8) showed continuity. An old sage at the field said "pull the plug" dude. We did and with the glow plug igniter installed we cranked up the voltage. The meter showed the right voltage but the "glow" plug hardly burned at all. I pulled a new #8 out of the box and hooked it up to the igniter and reran the test. The new plug glowed like the sun. Threw the old plug out and the engine runs beautifully.

hth,

airwarriorME109

j s,
I dont have an answer for you but just wanted to let you know that im experiencing the exact same problem on the second time out with a new engine. Im going to try using a A5 glow plug and new fuel the next time out. The engine runs so smooth and then just quits, very discouraging.

NM2K

My Feedback: (14)

I've scanned through all of the posts in this thread and I do not recall seeing anyone addressing the issue of fuel foaming. Fuel foaming, though an incorrect term, is the best term that we have come up with to describe the phenomenon of causing bubbling in the fuel tank that is induced by engine vibration shaking the fuel tank very hard. The bubbles in the fuel stream cause the mixture to change when the model is airborne. This can make guessing where to set the high speed needle appropriately nearly impossible. Many modern model ARF kits utilize solid mounting of the fuel tank, which transmits engine vibration directly to the fuel tank. Often, going to a smaller radiused, but longer, fuel tank can provide the modeler with enough room to install some soft, uncompressed foam rubber for isolating the fuel tank from the solid components of the fuselage. This technique also requires that none of the fuel tank solid plumbing be permitted to touch the firewall as it passes through toward the engine's carb.

Yes, this can be a PITA to accomplish, but it often makes those mysterious flame-outs disappear.

I used to burn Morgan's Cool Power fuel without a problem, as long as I kept the mixture properly rich and then only in engines that utilized bushed connecting rods on both ends. Today's OS engines are not the same as they used to be and some lack the requisite bushings in the connecting rods that I just mentioned. One can add four ounces of castor oil to Cool Power that has already been purchased and is residing in the larder. The extra four ounces of castor oil will make the Cool Power very similar to the Omega fuel that Dar mentioned. With fuel costing what it does these days, there's nothing wrong with trying to salvage the existing already owned Cool Power fuel by adding some castor oil.

Ed Cregger

Trisquire

Guess I should have posted more of the Dubb Jett quote:

frenchie79

Same exact thing happened this weekend to a friend on a AX46. He was using a 4 stroke fuel and I believe it was just getting hot. Ran fine on the ground and everything tested fine. Changed to a 2 stroke fuel and walla! More oil and cooler. The 55 is a fantastic engine and easy to tune, just be sure you have both needles more on the rich side than the lean side.
#8 plug, tank and lines good, right fuel. All the other advice above is right on if this won't work.

Turk1

I have seen some stopping problems in midflight and all have solved by fixing karbs.(Some fixed
 with a new carb, some fixed to dissassemble and reassemble of the carb)